Spinal cord injuries may arise from car accidents, violent crimes, falls and sports injuries. Spinal cord injury is a major neurological problem since most damage resulting from the injury is irreversible. Injured nerves fibers do not normally regenerate with resulting loss of nerve cell communication, leading to paralysis and loss of sensation.
After spinal cord severance, a new glial basal lamina forms to cover the exposed surface of the cord end regions. The glial cells also secrete barrier molecules that are difficult to penetrate, further suppressing reestablishment of nerve interconnections. The spinal cord tissue bordering the severed region becomes necrotic, detaches from the spinal cord, and develops irregular cavities.
Most tissue in the human body originates from undifferentiated cells known as stem cells. These fundamental building blocks differentiate into specific target parenchymal tissue based on hormonal signals. Scientific evidence suggests that stems cells injected into a target tissue will differentiate into a cell line specific to the host tissue. This capability is of particular interest in treating conditions involving organs, such as the spinal cord, that cannot regenerate.
Initial enthusiasm concerning stem cell implantation in patients was tempered by the ethical and logistic concerns of utilizing embryonic stem cells. Recent developments in stem cell research suggest adult stem cells can be harvested from the bone marrow and other tissues. Many such “cell lines” have been generated and are undergoing clinical evaluation. If successful, this work will obviate the moral and ethical dilemma of utilizing tissue from embryos for research.
While it has been suggested that stem cells could be used to repair spinal cord injury, there currently is no method or apparatus available to promote reestablishment of nerve pathways through the glial basal lamina or necrotic regions that develop at the injury situs. Accordingly, the suggestions in the prior art to use stem cells to regenerate damaged regions of the spinal cord remain more fantastic than practical. In addition, efforts to directly inject stem cells into an injured spinal cord region could both injure the cell membranes and disrupt the delicate intercellular matrix, thereby causing further injury to the target tissue.
In view of the foregoing, it would be desirable to provide methods and apparatus for treating severed or injured nerve pathways by delivering a bioactive matrix, e.g., stem cells, within or adjacent to an injured nerve pathway so as to span or bridge injured or necrotic portions. In this manner, the bioactive matrix may promote nerve regeneration to restore conductive pathways across the injured region.
It would be also desirable to provide methods and apparatus for treating nerve pathway injury by delivering a bioactive matrix so as to reduce the risk of injury to stem cells within the bioactive matrix or to the target tissue.
It would be further desirable to provide apparatus and methods for treating nerve pathway injury by delivering a bioactive matrix to damaged tissue to promote tissue regeneration, wherein the apparatus and methods reduce physical trauma to the bioactive matrix during delivery, and enhance the proportion of viable material delivered to the damaged tissue.
It further would be desirable to provide apparatus and methods for treating a nerve pathway injury that promotes regeneration of both sensory and motor nerves.